Heavier Seeds Research Articles

Landscape of massive black-hole spectroscopy with LISA and the Einstein Telescope

Measuring the quasi-normal mode~(QNM) spectrum emitted by a perturbed black-hole~(BH) --~also known as BH spectroscopy~-- provides an excellent opportunity to test the predictions of general relativity in the strong-gravity regime. We investigate the prospects and precision of BH spectroscopy in massive binary black hole ringdowns, one of the primary science objectives of the future Laser Interferometric Space Antenna~(LISA) mission. We simulate various massive binary BH population models, featuring competing prescriptions for the Delays between galaxy and BH mergers, for the impact of supernova feedback on massive BH growth, and for the initial population of high redshift BH seeds (light versus heavy seeds). For each of these scenarios, we compute the average number of expected events for precision BH spectroscopy using a Fisher-matrix analysis. We find that, for any heavy seed scenario, LISA will measure the dominant mode frequency within ${\cal O}(0.1) \%$ relative uncertainty and will estimate at least 3 independent QNM parameters within $1 \%$ error. The most optimistic heavy seed scenarios produce $\mathcal{O}(100)$ events with $1 \%$ measurability for 3 or more QNM quantities during LISA's operational time. On the other hand, light seed scenarios produce lighter merger remnants, which ring at frequencies higher than LISA's sensitivity. Interestingly, the light seed models give rise to a fraction of mergers in the band of Einstein Telescope, allowing for the measurement of 3 QNM parameters with $\sim 10 \%$ relative errors in approximately a few to ten events/yr. More precise BH spectroscopy in the light seed scenarios would require instruments operating in the deciHertz band.

The effect of pollination on the growth and reproduction of oilseed rape (Brassica napus)

Phenotypic plasticity is an organism's ability to alter its development and life history in response to environmental conditions. In plants, biotic and abiotic factors drive the distribution of resources between growth and reproductive traits. One such biotic factor is pollination. Studies show that wind and insect pollination enhance oilseed rape (Brassica napus) yield. However, the impact of pollination on resource allocation towards growth and reproduction is less understood. We conducted a controlled experiment to assess the effect of pollination on growth and functional reproductive traits. We compared two simulated supplementary pollen deposition methods (representing wind and insect pollination) alongside a non-supplementary control. Pollinated plants allocated resources towards growth and reproduction similarly, irrespective of deposition method. Plants receiving no supplementary pollination produced fewer seeds, allocating resources to growth, more prolific and persistent flowering, and heavier seeds. Pollinated plants had a reduced flowering period and were shorter, indicating resources were allocated to seed production rather than growth or the production of additional flowers. This allocation of resources from growth and flowering metrics can increase yield directly through increased seed production and indirectly through shorter plants and a reduced flowering period with seeds that mature earlier (agronomically beneficial traits).Wind and insect pollination can enhance and stabilise oilseed rape yield under various environmental conditions by acting in complementary ways. Since pollination limits yield in oilseed rape, it must be considered an input that can be actively managed. Successful management of pollination services requires growers to detect pollination deficits. Inadequately pollinated oilseed rape plants exhibit apparent morphological changes (e.g. taller plants that flower for longer), acting as an early warning to growers. Equipping growers with this knowledge provides them with a means of detecting deficits and thus enables them to take positive action to restore pollination services by introducing honeybees or enhancing wild pollinators.

The formation of the first quasars: the black hole seeds, accretion, and feedback models

ABSTRACT Supermassive black holes (SMBHs) of $\sim 10^9\, \rm M_{\odot }$ are generally believed to be the central engines of the luminous quasars observed at z ≳ 6, but their astrophysical origin remains elusive. To investigate the formation of these distant quasars, we perform a suite of zoom-in simulations on a favourable halo, with a mass of $\sim 10^{13}\, \rm M_{\odot }$ at z = 6 and a history of multiple major mergers, ideal for BH growth. We test BH seeds of $10 {\!-\!} 10^6\, \rm M_{\odot }$, and various accretion and feedback models, including thin-disc and slim-disc accretion. We find that abundant gas supply and efficient angular momentum transport by gravitational torques are critical to BH accretion, and that the final BH mass depends strongly on the seed mass and radiative efficiency which in turn depends on feedback model. In our simulations, heavy seeds of $\gtrsim 10^4\, \rm M_{\odot }$ can grow rapidly to SMBHs of $10^8 {\!-\!} 10^9\, \rm M_{\odot }$ by z ∼6 in both thin and slim disc accretion models, provided that the duty cycle of near-Eddington accretion with an Eddington ratio λEdd ≳ 0.6 is maintained at $\gtrsim 40{{\ \rm per\ cent}}$. In particular, for a $10^5\, \rm M_{\odot }$ seed, both our fiducial model and the supercritical accretion model with no spin produce bright quasars with SMBHs of $\sim 10^9\, \rm M_{\odot }$ at z ∼ 7.5. On the other hand, the light seeds of $\lesssim 10^3\, \rm M_{\odot }$ failed to grow to $10^8\, \rm M_{\odot }$ by z ∼ 6 in our simulations. We caution that the results are inconclusive due to limitations of our numerical methods and physical models, and we stress the need for further investigations on the growth of BH seeds with more advanced methods.

Cereal rye mulch biomass and crop density affect weed suppression and community assembly in no‐till planted soybean

AbstractThe use of multiple ecological weed management tactics may be an effective solution to weed management challenges associated with reducing tillage. An experiment was conducted to assess how soybean Glycine max (L.) Merr. density and cereal rye Secale cereale L. mulch biomass affected weed suppression and community assembly in no‐till production. Soybean was planted at five rates from 0 to 74 seeds m−2, and five cereal rye mulch levels were established from 0 to 2 times the ambient cereal rye biomass within each site–year. We assessed the effects of soybean density and cereal rye mulch biomass on weed suppression, weed community composition, and the functional structure of weed life cycle, emergence timing, seed weight, height, and specific leaf area traits. Weed suppression was influenced by a synergistic interaction between soybean density and cereal rye biomass. The functional dispersion (FDis) of all weed traits, when combined, was reduced by increased soybean density and mulch biomass, suggesting that high treatment intensities induced trait convergence. However, soybean density and cereal rye biomass had differing effects on the FDis and composition of individual traits, suggesting that these management practices represent unique filters during weed community assembly. Mulch biomass had a larger effect on annual weed suppression and weed community composition than soybean density. Farmers who utilize high biomass cover crop mulch for weed management may experience shifts in weed community composition toward an increased proportion of perennials and weeds with later emergence, heavier seeds, and shorter stature. Increasing soybean density may reduce perennial weed biomass, making it a valuable complement to high cereal rye mulch biomass. As such, weed management in no‐till soybean is enhanced by combining multiple practices, which can enable synergistic weed suppression and the management of diverse weed functional groups.

The Influence of Seed Characteristics on Seed Dispersal Early Stages by Tibetan Macaques.

Simple SummarySeed dispersal by frugivores is critical to forest regeneration. However, the Tibetan macaque’s seed dispersal function and the effect of seed physical characteristics on seed dispersal effectiveness need to be confirmed. We not only demonstrated that Tibetan macaques could act as seed dispersers, but we also investigated the effect of seed physical characteristics on gut passage time and seed damage rates. Smaller seeds are less likely to be damaged and remain for longer periods of time, whereas larger and heavier seeds are defecated more quickly. In our experiments, the seed-to-shell investment rate had no effect on the damage rate. Understanding the role of seed dispersal in primates can aid in the understanding of seed dispersal symbiosis.There are numerous ecological and evolutionary implications for the ability of frugivores to predate on fruits and consume or disperse their seeds. Tibetan macaques, which are considered important seed predators, typically feed on fruits or seeds. However, systematic research into whether they have a seed dispersal function is still lacking. Endozoochory allows seeds to disperse over greater distances by allowing them to remain in the animal’s digestive tract. Consumption of fruit may not imply effective seed dispersal, and the physical characteristics of seeds (e.g., size, weight, specific gravity, etc.) may influence the dispersal phase’s outcome. We conducted feeding experiments with three captive Tibetan macaques (Macaca thibetana) and nine plant seeds to determine the influence of seed characteristics on Tibetan macaques’ early stages of seed dispersal. The results revealed that the percentage of seed destruction (PSD) after ingestion was 81.45% (range: 15.67–100%), with the PSD varying between plant species. Among the three passage time parameters, the transit time (TT) (mean: 18.8 h and range: 4–24 h) and the time of seed last appearance (TLA) (mean: 100.4 h and range: 48–168 h) differed significantly between seed species, whereas the mean retention time (MRT) (mean: 47.0 h and range: 32–70.3 h) did not. In terms of model selection, PSD was influenced by seed size, weight, volume, and specific gravity; TT was influenced by seed-to-shell investment rate, weight, volume, and specific gravity; and TLA was influenced only by seed size. These findings imply that seeds with a smaller size, specific gravity, volume, and greater weight pass more easily through the monkeys’ digestive tracts. Particularly, seeds with a mean cubic diameter (MCD) of <3 mm had a higher rate of expulsion, larger volume, and weight seeds pass faster, while smaller remained longer. Tibetan macaques, as potential seed dispersers, require specific passage time and passage rates of small or medium-sized seeds. Larger and heavier seeds may be more reliant on endozoochory. Tibetan macaques have the ability to disperse seeds over long distances, allowing for gene flow within the plant community.

A proteomic analysis of Arabidopsis ribosomal phosphoprotein P1A mutant

Ribosomal proteins are involved in the regulation of plant growth and development. However, the regulatory processes of most ribosomal proteins remain unclear. In this study, Arabidopsis plants with the mutation in ribosomal phosphoprotein P1A (RPP1A) produce larger and heavier seeds than wild-type plants. A comparative quantitative label-free proteomic analysis revealed that a total of 215 proteins were differentially accumulated between the young siliques of the wild type and rpp1a mutant. Knockout of RPP1A significantly reduced the abundance of proteins involved in carboxylic acid metabolism and lipid biosynthesis. Consistent with this, a metabolic analysis showed that the organic acids in the tricarboxylic acid cycle and the carbohydrates in the pentose phosphate pathway were severely reduced in the mature rpp1a mutant seeds. In contrast, the abundance of proteins related to seed maturation, especially seed storage proteins, was markedly increased during seed development. Indeed, seed storage proteins were accumulated in the mature rpp1a mutant seeds, and the seed nitrogen and sulfur contents were also increased. These results indicate that more carbon intermediates probably enter the nitrogen flow for the enhanced synthesis of seed storage proteins, which might subsequently contribute to the enlarged seed size in the rpp1a mutant. SignificanceRibosomes are responsible for protein synthesis and are generally perceived as the housekeeping components in the cells. In this study, the knockout of RPP1A leads to an increased seed size through repressing carbon metabolism and lipid biosynthesis, and increasing the synthesis of seed storage proteins. Meanwhile, the abundance of seed storage proteins and the nitrogen and sulfur concentrations were increased in the mature rpp1a mutant seeds. The results provide a novel insight into the genetic regulatory networks for the control of seed size and seed storage protein accumulation, and this knowledge may facilitate the improvement of crop seed size.

Development of Vegetative Propagation Strategies for Balanites aegyptiaca in the Sahel, Niger

Forests have always been a source of wood, food, and medicine for the rural populations of the Sahel. Anthropogenic and animal pressures often lead to low tree recruitment rates and seedling survival. Under certain conditions, multipurpose species such as Balanites aegyptiaca have shown dramatic decreases in population numbers. The objective of the present study is to determine the natural colonisation behaviour of B. aegyptiaca and to develop vegetative propagation strategies. Surveys were carried out in the agroforest parklands of the Regional Centre for Agricultural Research of Maradi Research Station. An inventory was carried out in 1,500 m2 plots to determine the species’ regeneration methods. We then tested seed germination success, and suckering induction, air-layering, and stem cuttings were carried out to determine the techniques best suited for the propagation of B. aegyptiaca. It emerged from this study that in nature, B. aegyptiaca is propagated naturally by dispersion of seeds (81.2%), as well as by rejection of the strain (13.5%) and by suckering (5.2%). The germination test showed that heavy seeds (38.4%) germinated best because they have a higher nutrient reserve. With a success rate of 11.1%, distal suckers react better than proximal suckers (5.5%) because they quickly acquire relative independence from the mother plant. As for air-layering, stems with large diameters react better (53.3%) than those with small diameters (46.6%) because they have thicker bark and store a large amount of elaborate sap responsible for rhizogenesis. In the stem segment cutting test, cuttings of small diameter react better at 30.8% than those of large diameter (12.6%) because they have a higher number of meristematic tissues. The stem segment cuttings seem to be the best adaptable alternative to the natural propagation of B. aegyptiaca because it combines ease of use, low cost, and a significant success rate.

Size matters: variations in seagrass seed size at local scales affects seed performance

AbstractSeed size can have an impact on angiosperm reproductive fitness. Ecological theory predicts plants that will produce larger seeds in stressful environments to increase the chances of seedling survival and numerous small seeds in favourable conditions to increase the number of recruits. We measured seed morphology of the seagrass Heterozostera nigricaulis from four populations under differing environmental conditions in South East Australia. Seed size and mass among sites showed consistent differences over four flowering seasons. Seeds from exposed, ephemeral meadows (Blairgowrie, Edwards Point) were 19%–53% heavier than those from larger, stable meadows at more sheltered sites (Swan Bay, Point Henry). Overall, heavier seeds from exposed sites performed better in germination experiments and persisted (remained viable) longer compared to small seeds from sheltered sites. Seeds from sheltered sites showed contrasting levels of seed performance. Small seeds from Swan Bay had the lowest germination but the proportion of viable seeds after 12 months were much higher (41%) than similar sized seeds from Point Henry (0%). There are clear life history benefits of large seeds that facilitate seed persistence and germination at exposed sites; however, the performance of smaller seeds varied between sites and may be a function of other site-specific advantages.

Tracing astrophysical black hole seeds and primordial black holes with LISA-Taiji network

ABSTRACT In this work, we discuss the improvement that the joint network of LISA and Taiji could provide on exploring two kinds of black hole formation mechanisms. For astrophysical origin, we consider light seed and heavy seed scenarios, and generate populations accordingly. We find that the joint network has the potential to observe growing light seeds in the range 15 &amp;lt; z &amp;lt; 20, while single detector can hardly see, which would shed light on the light seeding mechanism. For the heavy seeds, the joint network only improves the signal-to-noise ratio. For primordial origin, we calculate the event rate at z &amp;gt; 20 and detection rates of LISA and the joint network. The joint network expands LISA’s horizon towards lower mass end, where the event rate is high, so we have better chance observing primordial black holes with the joint network. We also estimate the parameters using Fisher matrices of LISA and the joint network, and find that the joint network significantly improves the estimation.

Performance of Browntop Millet (Brachiaria ramosa L.) under Varied Spacing and Fertility Levels

Aims: Browntop millet is a warm season crop and it can produce heavy seeds compared to other millets. This crop grown on a variety of soils and climates. Brown top millet provide nearly all essential nutrients. Brown top millet referred as miracle or positive crop for the dry and rainfed situations. The Brown top millet is known for its rapid forage production.&#x0D; Study Design: The experiment was laid out in split plot design with three replications.&#x0D; Place and Duration of Study: An experiment was conducted for two consecutive Kharif seasons of 2019 and 2020 at Project Coordinating Unit, AICRP on Small Millets, Bangalore&#x0D; Methodology: Main plot was having three levels of fertilizer viz., F1(75 % RDF), F2(100% RDF) and F3(125 % RDF) and sub plot was accommodated with four different level of spacings viz., S1(22.5 cm X 10 cm), S2(30 cm X 10 cm), S3(45 cm X 10 cm) and S4(60 cm x 10 cm)&#x0D; Results: Results over years revealed that the plant height, number of tillers, 1000 seed weight, grain yield and straw yield found significantly higher with 125 per cent RDF however, was found on par with 100 per cent RDF. And regarding spacing, 45 cm x 10 cm was found optimum to realize higher yield.&#x0D; Conclusion: Spacing of 45 cm x 10 cm proved its significant dominance with plant height, number of tillers, 1000 seed weight, grain yield and straw yield as compared to other spacings tested. The nutrient uptake by crop and nutrient availability in soil also showed significantly higher values at 125 per cent RDF followed by 100 per cent RDF and again at the wider spacing level of 45 cm x 10 cm. All these results were further strengthened with higher economic parameters viz., gross return, net return and B:C ratio.

Genome-wide association studies dissect the genetic architecture of seed shape and size in common bean.

Seed weight and size are important yield components. Thus, selecting for large seeds has been a key objective in crop domestication and breeding. In common bean, seed shape is also important since it influences industrial processing and plays a vital role in determining the choices of consumers and farmers. In this study, we performed genome-wide association studies on a core collection of common bean accessions to dissect the genetic architecture and identify genomic regions associated with seed morphological traits related to weight, size, and shape. Phenotypic data were collected by high-throughput image-based approaches, and utilized to test associations with 10,362 single-nucleotide polymorphism markers using multilocus mixed models. We searched within genome-associated regions for candidate genes putatively involved in seed phenotypic variation. The collection exhibited high variability for the entire set of seed traits, and the Andean gene pool was found to produce larger, heavier seeds than the Mesoamerican gene pool. Strong pairwise correlations were verified for most seed traits. Genome-wide association studies identified marker–trait associations accounting for a considerable amount of phenotypic variation in length, width, projected area, perimeter, and circularity in 4 distinct genomic regions. Promising candidate genes were identified, e.g. those encoding an AT-hook motif nuclear-localized protein 8, type 2C protein phosphatases, and a protein Mei2-like 4 isoform, known to be associated with seed size and weight regulation. Moreover, the genes that were pinpointed are also good candidates for functional analysis to validate their influence on seed shape and size in common bean and other related crops.

Evaluating the impact of increased pollinator habitat on bee visitation and yield metrics in soybean crops

Agricultural intensification has significantly altered ecosystem functioning and aided in the reduction of global biodiversity. While agriculture requires increased reliance on animal pollination, pollinator populations have declined. To combat this, adding pollinator habitat into agricultural landscapes is increasingly common, but many questions remain about its functionality and impact on agroecosystems, particularly in pollinator-independent crops. Our study uses pollinator habitats planted on experimental research stations in the southeastern USA to evaluate their impact on pollinator communities within a nearby cropping system (soybeans) and the resulting yield. We found the species composition of pollinator communities within the habitat to be significantly different than the communities in soybeans. Even still, we identified more than 30 bee species visiting soybean flowers and verified that a subset of these species had actively collected soybean pollen. Bees from soybean fields planted adjacent to the habitat had more habitat pollen types present, while some species had more non-habitat types present when in the negative control sites. The presence of habitat had a positive effect on some yield measurements with adjacent soybean sites having 6.52% heavier seeds per plant on average. These findings demonstrate that pollinator habitat can be an important resource for supporting pollinators and highlights the importance of considering pollinator habitat in pollinator-independent crops, as they may still benefit from and be attractive to pollinator communities.

Exploring how functional traits modulate species distributions along topographic gradients in Baxian Mountain, North China

The associations between functional traits and species distributions across environments have attracted increasing interest from ecologists and can enhance knowledge about how plants respond to the environments. Here, we applied a hierarchical generalized linear model to quantifying the role of functional traits in plant occurrence across topographic gradients. Functional trait data, including specific leaf area, maximum height, seed mass and stem wood density, together with elevation, aspect and slope, were used in the model. In our results, species responses to elevation and aspect were modulated by maximum height and seed mass. Generally, shorter tree species showed positive responses to incremental elevation, while this trend became negative as the maximum height exceeded 22 m. Most trees with heavy seeds (> 1 mg) preferred more southerly aspects where the soil was drier, and those light-seed trees were opposite. In this study, the roles of maximum height and seed mass in determining species distribution along elevation and aspect gradients were highlighted where plants are confronted with low-temperature and soil moisture deficit conditions. This work contributes to the understanding of how traits may be associated with species occurrence along mesoscale environmental gradients.

Role of beneficial microbes with nitrogen and phosphorous levels on canola productivity

Abstract A research was conducted to evaluate the impact of various nitrogen and phosphorus levels along with beneficial microbes to enhance canola productivity. The research was carried out at Agronomy Research Farm, The University of Agriculture Peshawar in winter 2016-2017. The experiment was conducted in randomized complete block factorial design. The study was comprised of three factors including nitrogen (60, 120 and 180 kg ha-1), phosphorous (70, 100 and 130 kg ha-1) and beneficial microbes (with and without BM). A control treatment with no N, P and BM was also kept for comparison. Application of beneficial microbes significantly increased pods plant, seed pod, seed filling duration, 1000 seed weight, biological yield and seed yield as compared to control plots. Nitrogen applied at the rate of 180 kg ha-1 increased pods plant-1, seed pod, seed filling duration, seed weight, biological yield and seed yield. Maximum pods plant-1, seed pod, early seed filling, heavier seed weight, biological yield, seed yield, and harvest index were observed in plots treated with 130 kg.ha-1 phosphorous. As comparison, the combine treated plots have more pods plant-1, seeds pod-1, seed filling duration, heaviest seeds, biological yield, seed yield and harvest index as compared to control plots. It is concluded that application of beneficial microbes with N and P at the rate of 180 kg ha-1 and 130 kg ha-1, respectively, increased yield and its attributes for canola.

The Black Hole Mass Function Across Cosmic Times. I. Stellar Black Holes and Light Seed Distribution

Abstract This is the first paper in a series aimed at modeling the black hole (BH) mass function, from the stellar to the intermediate to the (super)massive regime. In the present work, we focus on stellar BHs and provide an ab initio computation of their mass function across cosmic times; we mainly consider the standard, and likely dominant, production channel of stellar-mass BHs constituted by isolated single/binary star evolution. Specifically, we exploit the state-of-the-art stellar and binary evolutionary code SEVN, and couple its outputs with redshift-dependent galaxy statistics and empirical scaling relations involving galaxy metallicity, star formation rate and stellar mass. The resulting relic mass function dN / dVd log m • as a function of the BH mass m • features a rather flat shape up to m • ≈ 50 M ⊙ and then a log-normal decline for larger masses, while its overall normalization at a given mass increases with decreasing redshift. We highlight the contribution to the local mass function from isolated stars evolving into BHs and from binary stellar systems ending up in single or binary BHs. We also include the distortion on the mass function induced by binary BH mergers, finding that it has a minor effect at the high-mass end. We estimate a local stellar BH relic mass density of ρ • ≈ 5 × 107 M ⊙ Mpc−3, which exceeds by more than two orders of magnitude that in supermassive BHs; this translates into an energy density parameter Ω• ≈ 4 × 10−4, implying that the total mass in stellar BHs amounts to ≲1% of the local baryonic matter. We show how our mass function for merging BH binaries compares with the recent estimates from gravitational wave observations by LIGO/Virgo, and discuss the possible implications for dynamical formation of BH binaries in dense environments like star clusters. We address the impact of adopting different binary stellar evolution codes (SEVN and COSMIC) on the mass function, and find the main differences to occur at the high-mass end, in connection with the numerical treatment of stellar binary evolution effects. We highlight that our results can provide a firm theoretical basis for a physically motivated light seed distribution at high redshift, to be implemented in semi-analytic and numerical models of BH formation and evolution. Finally, we stress that the present work can constitute a starting point to investigate the origin of heavy seeds and the growth of (super)massive BHs in high-redshift star-forming galaxies, that we will pursue in forthcoming papers.

Complex range shifts among forest functional types under the contemporary warming.

The direction and magnitude of species distribution shifts tend to differ among species and functional types (FTs). Quantifying functional trait variation and species interactions will improve our understanding of the complex mechanisms that govern ecosystem dynamics and their responses to climate change. Here, we analyzed differences in the juvenile and adult temperature ranges of Japanese tree species at the mean, colder edge, and warmer edge of their distributions to reveal how functional traits affect interactions between different FT groups (e.g., deciduous and evergreen broad-leaved trees), using linear models and permutation tests. Overall, juveniles preferred cooler sites, but with high variation. The variation among species was partly explained by the difference in seed mass where species with lighter seeds tend to colonize colder sites. On the other hand, the distribution range of FTs showed complex behavior at the ecotones of different FTs. Specifically, in three of eight ecotones, nonparallel range shifts between FTs were detected, which includes cold shifting in deciduous broad-leaved FT where a warm shift by subalpine FT happened, and cold shifting in subtropical FT where warm shifts by either the deciduous broad-leaved or the evergreen broad-leaved FTs happened. Our results suggest that past warming has caused a general cold shift at species level, whereas different mechanisms, such as light seeds disperse farther in distribution's colder edge and heavy seeds (e.g., evergreen broad-leaved) compete better in warmer edge, create nonparallel responses of FT distribution ranges leading to the observed homogenization at several ecotones among FTs. These complex range shifts at FT level have crucial implications for climate change mitigation and adaptation.

Long-term population dynamics of Aphelenchoides besseyi on Oryza sativa in a paddy field, and changes in the pathological and ecological traits of the two populations

Summary An Oryza sativa cultivar inoculated with the white tip nematode, Aphelenchoides besseyi, was cultivated over 18 years to investigate the population dynamics of the nematode and the change in the virulence of nematodes and tolerance/resistance of plants. The mean number of living nematodes per seed (S) showed two peaks, each of which was followed by a 3-year decrease in the S value, during the initial 10 years. The annual reproduction curve between in year and in year t had a peak in a range of of &lt;1.1. The incidence of white tip disease increased with increasing mean number of living nematodes seed−1 in the previous year, whereas the proportion of seeds with living nematodes increased with increasing mean number of living nematodes seed−1 in the current year. Inoculation tests of the nematode cohorts on the seedling cohorts derived from seeds harvested in the same or different years indicated that the initial 6-year interaction between the rice and nematode populations caused the nematodes to increase the incidence of white tip disease and to decrease the degree of seed swelling and the proportion of heavy seeds. On the other hand, the interaction caused the rice plants to prevent the incidence of disease from increasing and the degree of seed swelling and the proportion of heavy seeds from decreasing.

Plant seeds as source of nutrients and phytochemicals for the Indian population

SummaryPlant seeds are major sources of nutrients and bioactive compounds for human beings and vary across different locations. In addition, they are under used foods that could be a good complement for the daily nutrition of people. Therefore, the aim of this study was the analysis of different physical parameters, nutrients and bioactive compounds of 60 plant seeds belonging to 48 species and 9 families. The seeds were collected in 2016–2017 in the Raipur area, India (21.25°N 81.63°E), from three different locations. Fat, protein, starch, total polyphenols and mineral contents ranged from 0.7 to 44.2, 1.6 to 68.5, 11.3 to 84.0, 0.01 to 3.85 and 0.67 to 4.91 g/100 g (dry weight) respectively. Regarding physical properties, the heavier seeds were covered with thick testa over the range of 3.0 to 40% of the seed mass. Higher moisture and ash fractions for the starchy (cereal and pulses) and weed seeds were also found. The most abundant mineral elements in the seeds were P, S, K, Mg, Ca, Fe and Zn. Finally, it was calculated the contribution of the consumption of seeds to the daily macronutrients and micronutrients intake for Indian population, reaching up to 38, 13 and 25% for proteins, fat and carbohydrates respectively.

Seed ecology of European mesic meadows.

European mesic meadows are semi-natural open habitats of high biodiversity and an essential part of European landscapes. These species-rich communities can be a source of seed mixes for ecological restoration, urban greening and rewilding. However, limited knowledge of species germination traits is a bottleneck to the development of a competitive native seed industry. Here, we synthesize the seed ecology of mesic meadows. We combined our own experimental data with data obtained from databases to create a combined dataset containing 2005 germination records of 90 plant species from 31 European countries. We performed a Bayesian meta-analysis of this dataset to test the seed germination response to environmental cues including scarification, stratification, temperature, alternating temperature and light. We also used multivariate ordination to check the relationship between seed traits (germination and morphology) and species ecological preferences, and to compare the seed ecology of mesic meadows with that of other herbaceous plant communities from the same geographic area. The seed ecology of mesic meadows is characterized by (1) high seed germinability when compared with other herbaceous plant communities; (2) low correspondence between seed traits and species ecological preferences; and (3) a deep phylogenetic separation between the two major families, Poaceae and Fabaceae. Poaceae produce many light seeds that respond to gap-detecting germination cues (alternating temperatures and light); Fabaceae produce fewer heavy seeds, which need scarification to break their physical dormancy. High germinability of meadow seeds will reduce their capacity to form persistent seed banks, resulting in dispersal limitations to passive regeneration. For centuries, human activities have shaped the regeneration of meadows, leading to a loss of seed dormancy and decoupling seeds from seasonal cycles, as has been found in many domesticated species. The same anthropic processes that have shaped semi-natural mesic meadows have left them dependent on continued human intervention for their regeneration, highlighting the importance of active restoration via seed supply.

The search for the farthest quasar: consequences for black hole growth and seed models

ABSTRACT The quest for high-redshift quasars has led to a series of record-breaking sources, with the current record holder at z = 7.642. Here, we show how future detections of z &amp;gt; 8 quasars impact the constraints on the parameters for black hole growth and seed models. Using broad flat priors on the growth parameters (Eddington ratio $\, {f_{\rm Edd}}$, duty cycle ${\cal D}$, seed mass M•,seed, and radiative efficiency ϵ), we show that the large uncertainties in their determination decrease by a factor ∼5 when a quasar’s detection redshift goes from z = 9 to z = 12. In this high-redshift regime, ϵ tends to the lowest value allowed, and the distribution for M•,seed peaks well inside the heavy seed domain. Remarkably, two quasars detected at z &amp;gt; 7 with low accretion rates (J1243+0100 and J0313–1806) already tighten the available parameter space, requiring $M_{\rm \bullet , seed} \gt 10^{3.5} \, {\rm M_\odot }$ and ϵ &amp;lt; 0.1. The radiative efficiency is a crucial unknown, with factor ∼2 changes able to modify the predicted mass by ∼3 orders of magnitude already at z ∼ 9. The competing roles of inefficient accretion (decreasing ϵ) and black hole spin-up (increasing ϵ) significantly impact growth models. Finally, we suggest that yields currently predicted by upcoming quasar surveys (e.g. Euclid) will be instrumental for determining the most-likely seed mass regime. For example, assuming thin-disc accretion, a detection of a quasar with $M_\bullet \sim 10^{10} \, {\rm M_\odot }$ by z ∼ 9–10 would exclude the entire parameter space available for light seeds and dramatically reduce the one for heavy seeds.